The present invention relates to an X-ray data collecting apparatus and X-ray CT (computed tomography) apparatus, and more particularly to an apparatus for acquiring X-ray signals using an X-ray detector having a plurality of X-ray detector element rows, and an X-ray CT apparatus comprising such an X-ray data collecting apparatus.
At least one conventional X-ray CT apparatus is known that simultaneously acquires X-ray signals for a plurality of slices using an X-ray detector having a plurality of X-ray detector element rows arranged in parallel, and produces an image based on such X-ray signals. (For example, see Patent Document 1).
Moreover, at least one conventional technique for obtaining X-ray signals representing parallel beam X-rays from fan beam X-rays is known that involves adjusting signal collection times on an X-ray detector channel-by-channel basis. (For example, see Patent Document 2).
Furthermore, the X-ray signals are collected as integral values over a constant time period, and at least one conventional technique for obtaining reference X-ray signals adapted to varying collection times for different X-ray detector channels is known that involves repeating integration and resetting of the reference X-ray signals at subdivided times of the collection times, and summing the resulting plurality of integral signals over respective integral time periods for the channels. (For example, see Patent Document 3).
[Patent Document 1]
Japanese Patent Application Laid Open No. 2001-327386 (Pages 2-9, FIGS. 1-9).
[Patent Document 2]
Japanese Patent Application Publication No. H6-83709 (Pages 1-6, FIGS. 1-10).
[Patent Document 3]
Japanese Patent Application Publication No. H4-78258 (Pages 1-5, FIGS. 1-3).
By combining these conventional techniques, it is possible to construct an X-ray CT apparatus for collecting X-ray signals representing parallel beam X-rays from fan beam X-rays using an X-ray detector having a plurality of X-ray detector element rows, correcting the signals by reference X-ray signals, and producing an image based on the corrected signals.
Such a technique, however, obtains the reference X-ray signals at the collection times by summing signals obtained by repeating integration/resetting at subdivided times, and thus, the effective integration time for the reference X-ray signals is shorter than the integration time for measured X-ray signals, resulting in a corresponding decline of S/N (signal-to-noise ratio) of the signals.